When I accept an invitation to speak at a conference, I say "Yes, but I don't want to you to publish a video. If that's OK, then I'm in." Also, you may not realize this, but a lot of conferences are for-profit. It's not as if I'm tricking them by springing that constraint on them after the fact, and many of them are making money from the speakers' free labor to begin with.
Second, many many people have tried to build screencasting businesses. One of them turned into an 800 lb gorilla. Most of the rest don't exist any more. AFAIK, DAS was the second subscription-based screencasting company to exist, with the only prior art being a short-lived subscription option offered by TekPub (which was later acquired by the 800 lb gorilla). DAS still exists today, is still independent, and is still (almost) my only source of income, while dozens or maybe hundreds of others have come and gone. I'm sorry if you don't like the way I exercise control over my wholly-owned works, but my business model combined with control over my content has allowed me to do this successfully for six years (modulo a very long break in the middle). And I've never charged money for anything recorded at a conference; that wouldn't feel right.
Second, many many people have tried to build screencasting businesses. One of them turned into an 800 lb gorilla. Most of the rest don't exist any more. AFAIK, DAS was the second subscription-based screencasting company to exist, with the only prior art being a short-lived subscription option offered by TekPub (which was later acquired by the 800 lb gorilla). DAS still exists today, is still independent, and is still (almost) my only source of income, while dozens or maybe hundreds of others have come and gone. I'm sorry if you don't like the way I exercise control over my wholly-owned works, but my business model combined with control over my content has allowed me to do this successfully for six years (modulo a very long break in the middle). And I've never charged money for anything recorded at a conference; that wouldn't feel right.